Electrical Wiring & Estimation

Objectives:

To know about the following concepts

Selection of wiring & its types

Conditions and requirements for all domestics, commercial and industrial installation steps

Estimation and wiring calculation for domestic building

Wiring is systematic laying of wires for the smooth flowing of electricity current at different utility places with utmost safety and precautions.

Estimation is estimating wires and define the cost for installation.

Points to be considered for selection of wiring:

Initial cost: It should be economical.

Durability: It must be able to withstand wear and tear due to weather.

Safety from fire: It should be free from risk of fire as far as possible.

Mechanical protection: It must provide mechanical protection to the cables.

Permanency: The wiring must not be affected by the action of weather, fumes, dampness, chemicals etc.

Appearance: The appearance should be good enough to view.

Accessibility: It should be easy to extend or repair the wiring.

Life: The system should have good life time.

Maintenance cost: it should be low.

WIRING & ITS TYPES

1. Cleat wiring

2. Wooden casing and capping wiring

3. Lead sheathed wiring

4. Conduit pipe wiring

5. CTS or TRS sheath wiring

Cleat wiring:

1. Very simple method and cheapest one.

2. Single core PVC cables are used in this system.

3. Cleats are made up of porcelain and have two parts base piece and cap.

4. When wires are passed on to the walls or ceiling, they must taken through conduit pipes.

5. this system is not used in damp walls, ceilings.

6. Its life time is approximately 5 years.

Continued

Advantages:

Materials collected after removal installation can be used for further wiring

Expansion of wiring is possible

Fault can be easily identify

Disadvantages:

Less safety

Poor appearance

Cant used for permanent installation

Wooden Casing and Capping wiring

Casing and Capping wiring system was famous wiring system in the past. The cables used in this kind of wiring were either VIR or PVC or any other approved insulated cables.

The cables were carried through the wooden casing enclosures. The casing is made up of a strip of wood with parallel grooves cut length wise so as to accommodate VIR cables.

o The capping (also made of wood) used to cover the wires and cables installed and fitted in the casing.

Advantages of Casing Capping Wiring:

It is cheap wiring system as compared to sheathed and conduit wiring systems.

It is strong and long-lasting wiring system.

Customization can be easily done in this wiring system.

If Phase and Neutral wire is installed in separate slots, then repairing is easy.

Stay for long time in the field due to strong insulation of capping and casing..

It stays safe from oil, Steam, smoke and rain.

No risk of electric shock due to covered wires and cables in casing & capping.

Disadvantages of Casing Capping Wiring:

There is a high risk of fire in casing & capping wiring system.

Not suitable in the acidic, alkalies and humidity conditions

Costly repairing and need more material.

Material can’t be found easily in the contemporary

White ants may damage the casing & capping of wood.

Lead Sheathed Wiring

This types of wiring used for low voltage installation

This system requires good earthing

Sharp pending of the cables should be avoided

Advantages:

Protection from fire is good and mechanical protection is high

Disadvantages:

Not suited where fumes of acid are present.

Conduit Wiring

An electrical conduit is a tube used to protect and route electrical wiring in a building or nonbuilding structure. Electrical conduit may be made of metal, plastic, fiber, or fired clay.

There are two additional types of conduit wiring according to pipe installation

Surface Conduit Wiring

Concealed Conduit Wiring

Surface Conduit Wiring

If conduits installed on roof or wall, It is known as surface conduit wiring. in this wiring method, they make holes on the surface of wall on equal distances and conduit is installed then with the help of rawal plugs.

Concealed Conduit wiring

If the conduits is hidden inside the wall slots with the help of plastering, it is called concealed conduit wiring. In other words, the electrical wiring system inside wall, roof or floor with the help of plastic or metallic piping is called concealed conduit wiring. obliviously, It is the most popular, beautiful, stronger and commonelectrical wiring system nowadays.

Types of Conduit

Following conduits are used in the conduit wiring systems (both concealed and surface conduit wiring) which are shown in the above image.

Metallic Conduit

Non-metallic conduit

Metallic Conduit:

Metallic conduits are made of steel which are very strong but costly as well.

There are two types of metallic conduits.

Class A Conduit: Low gauge conduit (Thin layer steel sheet conduit)

Class B Conduit: High gauge conduit (Thick sheet of steel conduit)

Non-metallic Conduit:

A solid PVC conduit is used as non-metallic conduit now a days, which is flexible and easy to bend.

Advantage of Conduit Wiring Systems

It is the safest wiring system (Concealed conduit wring)

Appearance is very beautiful (in case of concealed conduit wiring)

No risk of mechanical wear & tear and fire in case of metallic pipes.

Customization can be easily done according to the future needs.

Repairing and maintenance is easy.

There is no risk of damage the cables insulation.

it is safe from corrosion (in case of PVC conduit) and risk of fire.

It can be used even in humidity , chemical effect and smoky areas.

No risk of electric shock (In case of proper earthing and grounding of metallic pipes).

It is reliable and popular wiring system.

sustainable and long-lasting wiring system.

Disadvantages of Conduit Wiring Systems

It is expensive wiring system (Due to PVC and Metallic pipes, Additional earthing for metallic pipes Tee(s) and elbows etc.

Very hard to find the defects in the wiring.

installation is not easy and simple.

Risk of Electric shock (In case of metallic pipes without proper earthing system)

Very complicated to manage additional connection in the future.

Size of Conduit:

The common conduit pipes are available in different sizes genially, 13, 16.2, 18.75, 20, 25, 37, 50, and 63 mm (diameter) or 1/2, 5/8, 3/4, 1, 1.25, 1.5, and 2 inch in diameter.

Fig: Conduit wiring

Batten Wiring (CTS or TRS) This type of wiring is also used for house wiring and its also quite cheap.

Cab Tyre Sheathed (C.T.S) wire or Tough Rubber Sheathed (T.R.S) wire is normally used as conductor for this wiring.

Advantages of Batten Wiring

Wiring installation is simple and easy

cheap as compared to other electrical wiring systems

Paraphrase is good and beautiful

Repairing is easy

strong and long-lasting

Customization can be easily done in this wiring system.

less chance of leakage current in batten wiring system

Disadvantages of Batten Wiring

Can’t be install in the humidity, Chemical effects, open and outdoor areas.

High risk of firs

Not safe from external wear & tear and weather effects (because, the wires are openly visible to heat, dust, steam and smoke.

Heavy wires can’t be used in batten wiring system.

Only suitable below then 250V.

Need more cables and wires.

Comparison between Different Wiring Systems

Types of wire used in wiring

Vulcanized Rubber wire

Weather proof wire

•It made waterproof by drooping it into waterproof compound

•It is useful for service connection

Lead covered wire

•No effect of moisture on it

•It used where there is moisture presence.

Mineral insulated copper covered

•Less effect of temperature.•Copper sheath is provided.•It is used in mines, factory, refinery, furnace, boiler, rolling, mill est.•Coating of magnesium oxide is provided.

Poly Vinyl Chloride wire

•Dielectric strength is more•Mechanical strength is more•Life is long•Protect against flame•Protect against oil, alkali•PVC wire is widely used

WIRING FOR DOMESTIC HOME & INDUSTRY

Condition for Domestic & Industrial Installation

Height of switch board must be 1.3m to 1.75m from floor level

Height of distribution board must be 1.5m to 1.75m from floor level

The bottom of ceiling fan should have minimum clearance of 2.75m

All lamp should be filled with a minimum clearance of 2.75m above floor level

Load should be equally shared

In any building light wiring and power wiring should be kept separate

Power per circuit may take it as 800w or 1000w

continued

Weatherproof wire for service connection with sufficient current carrying capacity.

All conductor/wire should be sage in all term of voltage rating with proper insulation.

Ever line or phase should be protected by suitable ratings fuse.

Each load point an appliances should be a independent control switch.

. In any light/fan and the number of load points connected in one sub circuit should be less than 10(ten).

In the bath rooms. the 3 pin socket should be at a height of not less than 1.5 m.

References

http://www.ustudy.in/eee/eest

http://aceee.org/files/proceedings/2012/data/papers/0193-000376.pdf

Electrical Wiring, Estimating and Costing: M.K.S. Units for Technical Schools, Industrial Institutes, N.C.C., State Diplomas, Electrician and Supervisory Courses S. L. Uppal, J. M. Laroia

http://www.electricaltechnology.org/2015/09/types-of-wiring-systems-electrical-wiring-methods.html

https://en.wikipedia.org/wiki/Electrical_wiring